The phenomenology of encoding: Experience sampling reveals thoughts associated with the retention of visual and...

Evaluating ongoing thoughts during behavioral tasks can offer valuable insight into underlying cognitive processes. Yet, despite their ubiquity, dimensions of thought are often overlooked in experimental psychology, where researchers typically prioritize the assessment of task performance and neglect the accompanying mental experience. In this study, we used experience sampling to investigate the phenomenology of task-unrelated and task-relevant thoughts during memory encoding for verbal and visual stimuli. In two experiments, participants studied words and images matched in intrinsic memorability before completing a recognition memory test. During the study phase, participants responded to several thought probes at pseudorandom intervals, rating dimensions of task-relatedness, awareness, unguidedness, inner speech, visual imagery, auditory imagery, bodily sensation, and emotion. Our results revealed a robust effect across experiments between task-unrelated thoughts (TUTs) and recognition failures, suggesting attention lapses interfere with encoding. Meta-awareness during TUTs showed a protective effect on encoding in Experiment 1 that did not replicate in Experiment 2, and modality-matched TUTs (e.g., visual TUT during image study) did not differentially impair memory. During task-oriented states, verbal stimuli evoked more auditory imagery, while visual stimuli evoked more unguidedness, visual imagery, and emotion. Importantly, certain on-task thought qualities, such as awareness and inner speech, were uniquely linked to enhanced memory performance, suggesting that task-relevant thoughts are heterogeneous in their role in processing and encoding. By emphasizing the intricate relationship between external stimuli, inner experience, and memory encoding, this work calls for a more integrative approach that incorporates phenomenological perspectives in the study of cognition.